Improved Solar Cells with Light Trapping Nano Holes

Another development to improve the efficiency of solar panels has been announced by researchers from Princeton University led by professor Stephen Chou. By using a nanostructured "sandwich" of metal and plastic, the efficiency of thin film solar collectors was improved by 175 percent.

The nanoscale lattice on top of the sandwich is able to trap light with openings called a "plasmonic cavity with subwavelength hole array" or PlaCSH. The layer is made of gold and is only 30 nanometers thick. Each hole is 175 nanometers in diameter and spaced 25 nanometers apart. The opening is smaller than the wavelength of light, which traps it rather than allowing it to reflect off the collector, which leads to improved conversion of light to electricity.

The mesh layer also replaces the indium-tin-oxide (ITO) layer which is typically on top of thin-film solar cells, which is one of the most expensive parts of these cells. The ITO layer is also more brittle, while the PlaCSH is extremely bendable.

image credit: Chou lab

via: Phys Org

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teacher
written by cccccttttt, December 12, 2012

Great work with lots of promise.

But why does the mesh have to be made of gold?

Graphene or something similar could offer the same

sub wavelength structure.

ct

Well colour me gold
written by IJustKnowStuff, December 19, 2012

I think it may be gold because it's easier to punch nano holes in a sheet of gold. This is obviously only a prototype, I doubt they would use gold as the end product (could be wrong, I don't know the math. How much gold gets used if production was scaled up?_

Good job
written by Green&Energy, December 20, 2012

I think this idea sounds great and very interesting.
So, I hope this project has a chance to be refined and realized in the future.

Gr8 concept!!!
written by Richard, December 23, 2012

This looks like to me an interesting innovation. Haven't heard of anything like this yet from anywhere.

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written by programme immobilier neuf, December 27, 2012

This is something very innovative. I never heard of such innovation. This will going to be very useful in future.

gold is not terribly expensive...
written by Hydrophilia, December 28, 2012

Don't worry about the cost of the gold: at $2000/oz a solid sheet 30nm thick would cost about $41/m^2, so if we allow for the holes it should only take about $25/m^2. Graphene is probably much more expensive for this use, but technologies change and it may become the material of choice.

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written by doug, December 29, 2012

How is it that light ever gets through in the first place if the holes are smaller than the wave length of light so the light is trapped under this layer. In one comment it is even described that it bends the rays in toward the surface in low or indirect light conditions. This sounds like a one way mesh: lets light in, but can't escape.

To follow up, has anything like this been observed on the surface of leaves? Maybe where efficiency is more critical i.e. ferns.

What happens if nano holes escape?
written by Pete, December 30, 2012

I am all for good uses of technology, however I am very concerned about these materials. What will happen if the nano holes come loose from their substrate? The nano holes would be free to float in the air and become lodged in peoples eyes, be breathed into lungs. What damage will these nano holes do once embedded in the human body?

Escaping holes
written by Simon West, January 03, 2013

Pete, I too am worried about the nano holes escaping... they could start clumping together and make bigger and bigger holes, and eventually the solar panel itself could fall into them! If too many escape the consequences could be dire. Forget "Grey Goo" from nanobots, nano holes are far more scary! smilies/shocked.gif

Happy New Year!

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